Strategies for offsite data protection: using snapshots to merge backup and archive in the cloud

People are far more familiar with cloud storage than they think. Hundreds of millions of people regularly store their photos and videos in the cloud. Every time someone posts a picture to Facebook, Flickr, or any social-networking or photo-sharing site, that photo is stored and protected in the cloud. The file is safely archived. This is a great use case for cloud storage - for reasons I'll detail below - but the cloud can be more than an archive. A snapshot-based cloud gateway can take advantage of the protection model of the cloud to transform its functionality for business.

Generally, people think of an archive as a structure or building, protected against weather and theft, that stores single copies of important documents or other items. The Declaration of Independence at the National Archives Building, for example.

Cloud storage systems rely on a very different method of data protection. In the cloud, newly stored data is tagged with an authentication signature, then copied. It doesn’t sit on one machine: Data is replicated to other servers, often in different geographic regions, so that it is always online and available to people who want to call it up, or machines programmed to copy it to another location. Because of the authentication signatures, these copies are all perfect. The effect is akin to creating indistinguishable clones of the Declaration of Independence and storing them in lock-down facilities across the country.

The cloud’s protection model guards against fallout from hardware failures and mistakes made when data is migrated from one server to another. Individual users benefit because they won’t lose beloved photos if they make an error moving their data from an old desktop to a new one. Businesses, on the other hand, pay cloud storage providers like Amazon and Rackspace to guarantee that their own critical data is preserved, and that multiple copies of archived data are being made.

Whether we’re talking about a satellite image, an X ray, or a final version of a critical business document, file archiving is a perfect use case for the cloud. You have a digital asset that you want protected, and you want to be able to pull back a perfectly accurate, pristine copy on-demand, whether that’s in ten days or ten years. The cloud does this so well because it is a system that is essentially designed to resist data modification. In most cloud storage systems, a modification of data is indistinguishable from data corruption. The system will fight to reverse the change. If a file is stored in the cloud, and a subsequent copy of that file is not absolutely perfect, it will be disregarded.

On the surface, this protection model might seem to limit the cloud’s functionality for business. The reality is that businesses don’t merely need archives. Files are constantly being modified. What constitutes a “final” version is often arbitrary – there’s no conscious decision to archive. Since it is so easy to make changes in a file system, businesses need to be able to roll back to specific points in time in the life of a given file in case a mistake was made, or unnecessary information added. That, of course, is why there is backup. Backup allows IT administrators to go back to previous versions and undo mistakes.

The cloud’s refusal to allow modifications to stored files doesn’t have to mean that it can’t be used for versioned backup. Originally introduced to the market by NetApp, snapshots capture an entire file system at a point in time. Snaphots can transform the traditional read/write file system into a series of file system archives that cannot be modified and are, therefore, perfect targets for cloud storage. A cloud gateway uses snapshots to merge backup and archive, delivering the best of both.

The protection model of the cloud might hate changes, but with snapshots, those changes can be stored as separate chunks of data. The altered chunks of data then become newly archived items. This way, when a user rolls back to an older version of a given file, the gateway will pull together the complete file from the separately archived pieces.

The Nasuni Filer uses snapshots to archive versions of your file system to the cloud. This eliminates the need for making backups even as the files are changing. The Filer ensures that critical files are stored unchanged in the cloud. Snapshots allow you to roll back to previous versions or points in time in the file system. (And it will get easier still in our upcoming release.) In effect, all versions are treated as critical, archive-worthy items.

Again, we have nothing against using the cloud as an archive. It is a great use case. But with the right cloud gateway technology, it can offer so much more to the modern data-heavy business.

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